【作者】 马丰华；

【导师】 徐习东；

【作者基本信息】 浙江大学 ， 电力系统及其自动化， 2007， 硕士

【摘要】 本文对电力变压器保护励磁涌流问题进行了深入的研究，提出了一种励磁涌流研究中计算磁化曲线的新方法，并给出了新型变压器保护原理中需要的漏电感、励磁电感参数的计算方法。由于电力系统对安全性的要求，原理简单、灵敏度比较高的差动保护仍然是变压器保护中应用最为广泛的方法。励磁涌流问题是影响变压器差动保护性能的重要因素。文章在综述了励磁涌流的产生机理后，对励磁涌流的各种识别方法进行了分析比较，并指出了其缺陷。励磁涌流识别需要变压器基本磁化曲线参数，磁化曲线的设定会直接影响到涌流和谐波计算。本文从考虑铁芯损耗的空载单相变压器模型出发，提出了直接利用变压器励磁磁链与磁化电流关系来分段线性化计算基本磁化曲线的全新方法。该方法充分利用变压器励磁电压电流关系和空载实验的各种已知数据，可以根据需要调节计算精度。根据电力变压器铁心磁导率在励磁涌流与内部故障时会有不同，应用等效瞬时电感的概念可以判别变压器励磁涌流；根据变压器内部故障时漏电感会发生明显的变化这一特性，近年有等值参数法和变压器回路方程法等不同于差动保护原理的保护方法出现。这些新型的变压器保护方法都需要计算相关的电感参数。为此，本文总结提出了变压器漏电感和等效瞬时电感的计算方法。本文主体部分为四章。第二章介绍了励磁涌流产生机理和各种涌流识别方法；第三章提出了一种改进的磁化曲线的计算方法；第四章描述了计算漏电感和励磁电感的方法；第五章对现在变压器保护方法进行了反思，并展望了变压器保护未来的发展方向。各章都有严谨的推理和相应的仿真验证，以不同的视角对变压器保护进行了研究。更多还原

【Abstract】 This paper studies on some problems of power transformer inrush current, presents a new method to calculate magnetization curve, and prompts kinds of approaches for computing leakage inductance and excitation inductance used in novel principles of power transformer protection.For the strictly requirements in security and limitations of new protection methods , differential protection method, which is considered to be simple and sensitive , is still extensively used in the power protection field. Inrush current discrimination is one of the most important factors that influence protection performance. After the concept of inrush current is introduced, the existing methods for discriminating inrush are discussed.Inrush current discrimination bases on the magnetization curve of a certain transformer, and the form of magnetization curve effects the calculation of inrush and harmonic components. A new piecewise linearized approach, which takes account of iron core losses and bases on the transformer test data provided by the manufacturer, is presented for the computation of the saturation characteristics iron cores, and has obvious advantages over others. The accuracy can be easily controlled.Distinguishing magnetizing inrush currents from internal faults can be effectively fulfilled by using the criterion of an instantaneous excitation inductance and an equivalent instantaneous inductance, which is based on the difference of the magnetic permeability in iron core of transformer between inrush currents and internal fault. Recent years, there are two novel principles have been proposed basing on leakage inductance parameters vary obviously during internal faults. All of these methods require calculation of inductance parameters. Therefore, some advanced computational methods are proposed in this paper. The results of experimental tests show that these proposed methods are correct and effective.There are four chapters in main body. Chapter 2 introduces the concept and discrimination methods of inrush current; Chapter 3 presents a novel approach for computing magnetization curve; Chapter 4 describes how to calculate leakage and excitation inductances; In reviews of the protection means, Chapter 5 gives the prospective protection methods.更多还原